safety of radioactive waste and spent fuel...
TRANSCRIPT
Gerard BRUNO
Unit Head
Radioactive Waste and Spent Fuel Management
IAEA
Safety of Radioactive Waste and Spent Fuel Management
Global need for RWM: Sources of
waste
• Waste and spent fuel generation from NPPs
• Decommissioning of nuclear facilities
• Medical applications and research
• Remediation activities on-going in several countries,
– Activities after Fukushima accident will result in large volumes of
waste from on-site and off-site decommissioning and remediation
• Numerous sites with a large amount of legacy waste
– Radium industry
– Uranium mining
– Military programs
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IAEA and Radioactive Waste
Management
• The IAEA programme on Safety of Radioactive Waste and
Spent Fuel Management
– Support to the IAEA Member States in establishing a proper safety
framework for the management of radioactive waste and spent fuel.
• Activities
– Development of IAEA safety standards for predisposal management and
disposal of radioactive waste and spent fuel,
– Assistance to the Member States on the implementation and application of
the Safety Standards,
– Coordination of the Waste Safety Standards Committee.
• Joint convention
– Meetings of Contracting Parties of the Joint Convention on the Safety of
Spent Fuel Management and on the Safety of Radioactive Waste
Management.
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Article III, Functions Paragraph A.6.
“ To establish or adopt, in consultation and, where
appropriate, in collaboration with the competent
organs of the United Nations and with the specialized
agencies concerned,
standards of safety for protection of health and
minimization of danger to life and property (including
such standards for labour conditions), and
to provide for the application of these standards to
its own operation as well as to the operations making
use of materials, services, equipment, facilities, and
information made available by the Agency …; “
IAEA Statutory Obligations (1957)
Statute 1957
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IAEA Safety Standards Categories
Fundamental Safety Principles
Requirements – Legal, Technical,
& Procedural Safety Imperatives
Guidance on Best Practice
to Meet Requirements
Safety Guides
Safety Requirements
Safety Fundamentals
5 5
Structure of Safety Standards
6 6
CSS
COMMISSION ON SAFETY
STANDARDS
NUSSC RASSC WASSC TRANSSC
Safety Standards Committees
Commission and committees
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Safety Standards: Predisposal of RW
DS 448
Predisposal
Management of
RW from
Reactors
DS 447
Predisposal
Management of
RW from FCFs Under revision
to include
lessons leant
from
Fukushima
accident
DS 477
Revision
DS 489
DS 454
Revision
In publication In publication
Safety Standards for
Disposal
Revision
DS 477
• Policy document of the IAEA Safety Standards Series:
• States the basic objectives, concepts and
principles involved in ensuring protection
and safety
• Comprised of 10 safety principles
• Principle 7: Protection of present and future generations. People and the environment, present and future, must be protected against radiation risks
Safety Fundamentals
Safety fundamentals
• Responsibility for safety
• Role of government
• Leadership and management for
safety
• Justification of facilities and activities
• Optimisation of protection
• Limitation of risks to individuals
• Protection of present and future
generations
• Prevention of accidents
• Emergency preparedness and
response
• Protective actions to reduce existing
or unregulated radiation risks
SF-1
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1. Government responsibilities
2. National Policy & Strategy
3. Regulatory Responsibilities
4. Operator Responsibilities
5. Safety/Security
6. Interdependences
7. Management systems
8. Waste minimization
9. Characterization and classification
10. Waste treatment
11. Waste storage
12. Waste acceptance for processing, storage and/or disposal
13. Prepare safety case and supporting safety assessment
14. Safety case scope and regulatory compliance
15. Safety case documentation
16. Periodic safety review
17. Facilities location and design
18. Facility construction and commissioning
19. Facilities operation, maintenance, emergency preparedness
20. Decommissioning
21. Nuclear safeguards
22. Existing facilities
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Interdependences among all steps in the predisposal
management of radioactive waste, as well as the impact
of the anticipated disposal option, shall be appropriately
taken into account.
• Achieved principally through government and regulatory requirements
• Important to consider the established acceptance criteria for disposal of
the waste or the criteria that are anticipated for the most probable
disposal option
Requirement 6: Interdependences
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All radioactive waste shall be identified and controlled.
Radioactive waste arisings shall be kept to the minimum
practicable.
• Measures to control the generation considered in design and operation
• The authorized discharge of effluent and clearance of materials considered
Req. 8: Radioactive waste generation and control
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At various steps in the predisposal management of radioactive waste,
the radioactive waste shall be characterized and classified in
accordance with requirements established or approved by the
regulatory body.
– Characterized in terms of its physical, mechanical, chemical, radiological and biological properties
– The characterization serves to provide information relevant to process control and assurance that the waste or waste package will meet the acceptance criteria for processing, storage, transport and disposal of the waste
– Classification has to be made from the perspective of its future disposal
Requirement 9:
Characterization and classification of radioactive waste
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Radioactive material for which no further use is foreseen and with
characteristics that make it unsuitable for authorized discharge,
authorized use or clearance from regulatory control shall be processed
as radioactive waste.
The processing of radioactive waste shall be based on appropriate
consideration of the characteristics of the waste and of the demands
imposed by the different steps in its management (pretreatment,
treatment, conditioning, transport, storage and disposal). Waste
packages shall be designed and produced so that the radioactive
material is appropriately contained during both normal operation and in
accident conditions that could occur in the handling, storage, transport
and disposal of waste.
• To enhance safety by producing a waste form, packaged or unpackaged, that
fulfills the acceptance criteria for safe processing, transport, storage and disposal
of the waste
• Waste is rendered into a safe and passive form for storage or disposal as soon as
possible
Requirement 10: Processing of radioactive waste
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Waste shall be stored in such a manner that it can be inspected,
monitored, retrieved and preserved in a condition suitable for its
subsequent management.
Due account shall be taken of the expected period of storage, and, to
the extent possible, passive safety features shall be applied. For long
term storage in particular, measures shall be taken to prevent the
degradation of the waste containment.
– Temporary placement in a facility with appropriate isolation and monitoring
– Between and within the basic steps of management
– By definition an interim measure, can last for several decades
– Intention in storing waste is that it be retrieved
Requirement 11: Storage of radioactive waste
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Classification of RW
Different ways to classify waste
– By origin: Nuclear fuel cycle, isotope production,..
– By physical state: Solid, liquid, gaseous
– By activity concentration: LLW, ILW, HLW
– By half-life: Short-lived waste, long-lived waste
– By Operational or disposal purposes, heat emitting or
not…
Half-life
Activity
content
VSLW
very short lived
waste
(decay storage)
HLW
high level waste
(deep geologic disposal)
ILW
intermediate level waste
(intermediate depth disposal)
LLW
low level waste
(near surface disposal)
VLLW
very low level waste
(landfill disposal)
EW
exempt waste
(exemption / clearance)
WASTE TYPES & RELEVANT
DISPOSAL OPTIONS
Activity, half-life
VSLW VLLW LLW ILW HLW
Waste that meets the criteria for
clearance, exemption or exclusion
from regulation control for radiation
purposes as described in Safety
Guide RS-G-1.7 “Application of the
Concepts of Exclusion, Exemption
and Clearance” (2004)
Exempt Waste (EW)
• Does not necessarily meet the criteria of exempt waste
• Does not need a high level of containment and isolation
• Suitable for disposal in near surface landfill type facilities
with limited regulatory control
• Typical waste includes soil and rubble with low levels of
activity concentration
• Concentrations of longer lived radionuclides are generally
very limited
Very Low Level Waste (VLLW)
• Waste that can be stored for decay over a limited period of
up to a few years and subsequently cleared from
regulatory control for uncontrolled disposal, use or
discharge.
• This class includes waste containing primarily
radionuclides with very short half-lives often used for
research and medical purposes.
Very Short Lived Waste (VSLW)
• Above clearance levels, but with limited amounts of long
lived activity
• Requires robust isolation and containment for periods of up
to a few hundred years
• Suitable for disposal in engineered near surface facilities
• LLW cover a broad range of materials and may include:
– SL radionuclides at higher levels of activity concentration and
– LL radionuclides but at relatively low levels of activity concentration
Low Level Waste (LLW)
• Greater degree of containment and isolation than that
provided by near surface disposal
• But no provision for heat dissipation during storage and
disposal
• May contain LL radionuclides, in particular alpha
emitting radionuclides
– Will not decay, during the IC period, to level of activity conc.
acceptable for NS disposal
– Disposal at greater depths than near surface disposal
Intermediate level waste (ILW)
• Levels of activity concentrations high enough to generate significant quantities of heat by the radioactive decay process
or
• Large amounts of long lived radionuclides that need to be considered in the design of a disposal facility for such waste
• Disposal in deep, stable geological formations, usually several hundreds m or more is the generally recognized
option for disposal
High Level Waste (HLW)
The specific aims of disposal
W
A
S
T
E
B
I
O
S
P
H
R
E
CONTAIN
ISOLATE
INHIBIT, REDUCE,
DELAY
SOURCE SAFETY FUNCTIONS
RECIPIENT OBJECTIVE
LOW
IMPACT
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Disposal – Safety
Requirements Applicable to disposal of all types of
waste in designed disposal facilities
Covers
• Operational phase
• Post-closure phase
Does not address o Broader issues of site selection o Transportation of waste to the site o Non radiological environmental
impact
Stakeholder involvement important, but beyond the scope of the standard
Consistent with ICRP Publications
77, 81 and 103
A total of 26 requirements
SAFETY REQUIREMENTS
DISPOSAL OF RADIOACTIVE WASTE
• REQUIREMENTS FOR PLANNING DISPOSAL FACILITIES
o LEGAL AND ORGANIZATIONAL FRAMEWORK
o SAFETY APPROACH
o SAFETY DESIGN PRINCIPLES
• REQUIREMENTS FOR THE DEVELOPMENT, OPERATION AND CLOSURE OF DISPOSAL FACILITIES
o FRAMEWORK FOR DISPOSAL
o THE SAFETY CASE AND SAFETY ASSESSMENT
o STEPS IN THE DEVELOPMENT, OPERATION AND CLOSURE OF DISPOSAL FACILITIES
• REQUIREMENTS FOR ASSURANCE OF SAFETY
• EXISTING DISPOSAL FACILITIES
Req. 5: Passive means for the safety of the
disposal facility
The operator shall evaluate the site and shall design, construct, operate and close the disposal facility in such a way that safety is ensured by
passive means to the fullest extent possible and the need for actions to be taken after closure of the facility is minimized.
• Operational stage: certain active control can be applied but if passive features (e.g. shielding, containment by package) can provide safety they should be used
• To some extent safety can depend on future actions (e.g. maintenance work) but this dependence has to be minimized
• Geological disposal facility and borehole: possible to provide for safety after closure by means of passive features (owing e.g. to the host geology)
• But for near surface disposal actions such as maintenance, monitoring and surveillance may be necessary for a period after closure
• It is the performance of the natural and engineered barriers that provides safety after closure
The host environment shall be selected, the engineered barriers of the facility shall be designed and the facility shall be operated to ensure that safety is provided by means
of multiple safety functions.
Containment and isolation of the waste shall be provided by means of a number of physical barriers of the disposal system.
The performance of these physical barriers shall be achieved by means of diverse physical and chemical processes together with various operational controls.
The capability of the individual barriers and controls together with that of the overall disposal system to perform as assumed in the safety case shall be demonstrated.
The overall performance of the disposal system shall not be unduly dependent on a single safety function.
• Engineered and physical barriers are physical entities, such as the waste form, the
packaging, the backfill, and the host environment.
• A safety function may be provided by means of a physical or chemical property or process
contributing to containment and isolation (e.g. impermeability, retention of radionuclides)
• Barriers and safety functions can be complementary and can work in combination
• The safety case has to explain the functions performed by the components and to identify the
time periods over which they are expected to perform
Req.7: Multiple safety functions
The engineered barriers, including the waste form and packaging, shall be designed, and the host environment shall be selected, so as to provide
containment of the radionuclides associated with the waste. Containment shall be provided until radioactive decay has significantly reduced the
hazard posed by the waste. In addition, in the case of heat generating waste, containment shall be provided
while the waste is still producing heat energy in amounts that could adversely affect the performance of the disposal system.
• Design the disposal facility to avoid or minimize the release of radionuclides
• The containment may be provided by the characteristics of the waste form and the
packaging and by the characteristics of other engineered components of the disposal
system and the host environment
• The containment has to ensure that the majority of shorter lived radionuclides decay in
situ.
• For low level waste, such periods would be of the order of several hundred years;
• For high level waste the period would be several thousands of years.
Req. 8: Containment of radioactive waste
Req. 9: Isolation of radioactive waste
The disposal facility shall be sited, designed and operated to provide features that are aimed at isolation of the radioactive waste from
people and from the accessible biosphere.
The features shall aim to provide isolation for several hundreds of years for short lived waste and at least several thousand years for intermediate and high level waste.
In so doing, consideration shall be given to both the natural evolution of the disposal system and events causing disturbance of the facility.
• Keep the waste and its associated hazard apart from the accessible biosphere.
• Minimize the influence of factors that could reduce the integrity of the disposal facility.
• Provide for a very slow mobility of radionuclides for migration from disposal facility.
Near surface facilities: isolation provided by the location and the design of the
disposal facility and by operational and institutional controls.
Geological disposal: isolation provided primarily by the host geological
formation as a consequence of the depth of disposal.
Concept Siting Development Operation Post closure
Design Excavation waste
emplacement
IC Beyond IC
Government
Operator
Regulator
Safety Case
Project stages / time frame
Pre-operational period Operational
period
Post-closure period
The concept of Safety Case in the
IAEA • The concept of Safety Case has been circulated for many years.
• The NEA defines the Safety Case as : “The synthesis of evidence,
analyses and arguments that quantify and substantiate a claim that the
repository will be safe after closure and beyond the time when active
control of the facility can be relied on”.
• IAEA defines it as the collection of arguments and evidence to
demonstrate the safety of a facility.
• The SC has to be developed in the early phases of the development of
a project. For the operator as a basis for internal decisions (R&D, site
selection and evaluation, design conceptualization…) as well as for
dialogue with the regulator
The concept of Safety Case in the IAEA
• Requirement 12: Preparation, Approval and use of the safety case and safety
assessment for a disposal facility
“A safety case and supporting safety assessment shall be prepared and updated by the operator, as
necessary, at each step in the development of a disposal facility, in operation and after closure. The
safety case and supporting safety assessment shall be submitted to the regulatory body for approval.
The safety case and supporting safety assessment shall be sufficiently detailed and comprehensive to
provide the necessary technical input for informing the regulatory body and for informing the
decisions necessary at each step”
• Requirement 13: scope of the Safety Case and safety assessment
The safety case for a disposal facility shall describe all safety relevant aspects of the site, the design of
the facility, and the managerial control measures and regulatory controls. The safety case and
supporting safety assessment shall demonstrate the level of protection of people and the environment
provided and shall provide assurance to the regulatory body and other interested parties that safety
requirements will be met”
• Requirement 14: Scope of the Safety Case and Safety Assessment
The safety case and supporting safety assessment for a disposal facility shall be documented to a level
of detail and quality sufficient to inform and support the decision to be made at each step and to allow
for independent review of the safety case and supporting safety assessment”
System Description Site and waste characteristics, Safety Functions, Design Options
Safety Case Context
• Safety objectives
• Safety principles
• Regulations
Safety Strategy • Isolation, Containment
•Passive systems, robustness
•Defence in depth, demonstrability
Integration of Safety Arguments Demonstration of robustness, defence in depth
system understanding, monitoring, etc
En
viro
nm
en
tal
Imp
act
Op
era
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l
Sa
fety
Site / E
ng
ineerin
g
Assessments
S
takeh
old
er & R
egulato
ry In
volv
emen
t
Limits & conditions e.g. WAC
Man
agem
ent
System
Iteration &
Desig
n O
ptim
isation
Man
agem
ent o
f Un
certainty
Po
st-Clo
sure
radio
log
ical imp
act
M
anag
emen
t Sy
stem
Atoms for peace
and development
at your service for 60 years…
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